The present invention relates to a telephone set, in particular to a portable telephone set.
Battery-operated portable wireless telephone sets ranging from vehicular models to pocketsize sets have come into common use. Many portable telephone sets have functions not found in wired telephone sets. A simple example is a power switch enabling the telephone set to be switched off when calls are not expected, to conserve battery power.
Another feature is a volume control that can adjust the loudspeaker volume for use in various environments. Many portable telephone sets store the volume setting in a non-volatile memory while power is switched off, and restore the same setting the next time power is switched on, so that the user does not have to adjust the volume every time the telephone set""s power is switched on.
Many portable telephone sets also have an expanded range of loudspeaker volume settings, including very soft and very loud settings. The very soft setting is used to avoid disturbing people nearby, or to avoid having a telephone conversation overheard. The very loud setting is used in noisy environments, to make the distant party""s voice audible.
Another function found in many portable telephone sets is a vibration function that alerts the user to arriving calls by means of a vibrator. This function is useful in noisy environments, and in situations in which the user does not want to disturb people nearby.
Yet another function is a selection of different types of ringing tones, as taught in Japanese Unexamined Patent Publication No. 202994/1995. This function enables the user to distinguish the ringing tone of his or her telephone set from the ringing tones of other nearby telephone sets.
Still another function is a selection of hold melodies and other sound effects, sometimes including loud non-musical sound effects that can be used to discourage malicious callers.
A further function is a small liquid-crystal display panel that displays the time, date, telephone numbers, battery status, short messages, and other relevant information.
A still further function, taught in Japanese Unexamined Patent Publication No. 237393/1996, is an interface enabling the telephone set to be connected to a television set, so that the above information, and possibly other information such as images, not necessarily relevant to telephone communication, can be displayed on a large screen.
Although useful, these functions also make the telephone set more complex and more difficult to operate, and invite various types of operation mistakes. For example, if the user selects the very loud volume setting while using the telephone set in a noisy environment, and forgets to reset the volume when the call is finished, a later call in a more quiet environment may startle the user or people nearby. If the user selects the very soft volume while using the telephone set during a meeting, and forgets to reset the volume, a later call in a different environment may be difficult to hear, requiring a hasty readjustment of the volume.
Many telephone sets have a first loudspeaker for use when held close to the ear, and a second loudspeaker for use at a distance from the ear. The very soft and very loud volume settings are useful with the first loudspeaker, but if these settings are transferred inadvertently to the second loudspeaker, the distant party""s voice becomes barely audible or disturbingly loud.
Selection of the vibration function is troublesome because the user must also decide whether to enable or disable the ringer, and whether to increase or decrease the microphone sensitivity, these decisions depending on whether the vibration function is used in a quiet or noisy environment. The user is required to make multiple settings for each situation.
The utility of a selection of different ringing tones is limited, because these ringing tones tend to sound alike. Identification of a particular ringing tone can be especially difficult when the telephone is carried in a purse or briefcase, or in an inner pocket under heavy clothing.
The utility of sound effects in discouraging malicious callers is offset by the misuse of the same sound effects to originate malicious calls.
The utility of a display of the date and time is limited because a person using a portable telephone set is likely to be wearing a wristwatch that gives the date and time more conveniently. Furthermore, the generally drab displays found on conventional portable telephone sets compare unfavorably with the attractive and fashionable dial faces of wristwatches. In addition, the display of fixed information such as telephone numbers during standby periods is uninteresting, and may give the false impression that the telephone set is malfunctioning, because the information does not change.
Connection of a portable telephone set to a television set quickly drains the battery of the telephone set, thereby lessening the utility of the telephone set for communication purposes.
Thus for various reasons, conventional portable telephone sets are somewhat difficult to operate, and their sound effects and display functions are not as useful as might be desired.
In a preferred embodiment of the present invention, a telephone set includes a receiving circuit, a display panel, and an input unit with manual controls. The memory unit stores a plurality of images. A control unit monitors elapsed time and input from the input unit. The control unit selects the images from the memory unit, displays the images on the display panel, and automatically switches the display panel from displaying the images to displaying information when a call is received by the telephone set. The images are automatically displayed after a predetermined time period has elapsed, during which the telephone set has entered and remained in a standby state waiting for a call to arrive, without an input from the input unit. While displaying the images, the display panel also displays an indication of whether the telephone set is within communicable range of a base station.
In an alternate embodiment of the present invention, a telephone set includes a display panel, a memory unit, an indicator circuit and a control unit. The memory unit stores a plurality of images. The indicator circuit operates independent of the display panel. The control unit selects the images from the memory unit, displays the images on the display panel, and automatically switches the display panel from displaying the images to displaying information when a call is received by the telephone set. Telephone communication information is presented by the indicator circuit when the images are displayed, and the telephone communication information is presented by the display panel when the images are not displayed.
In yet another embodiment of the present invention, the control unit automatically switches the display panel from displaying information to displaying the images a predetermined time after the telephone set enters a standby mode.